Identifying aphid resistance in the ancestral wheat Triticum monococcum under field conditions.
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SUBMITTER: Simon AL
PROVIDER: S-EPMC8241983 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundDomesticated einkorn (Triticum monococcum L.) is one of the oldest cultivated cereal crops in the world. Its small genome size (~ 5.7 GB), low ploidy (2n = 2x = 14, AmAm) and high genetic polymorphism make this species very attractive for use as a diploid model for understanding the genomics and proteomics of Triticeae. Einkorn, however, is still a recalcitrant monocotyledonous species for the application of modern biotechnologies, including transgenesis. This paper reports the factors that may influence transgene delivery, integration, expression and inheritance in einkorn.ResultsIn this study, we report the successful genetic transformation of einkorn using biolistic-mediated DNA delivery. Immature embryo-derived tissues of spring einkorn were bombarded with a plasmid containing the reporter gene GFP (green fluorescent protein) driven by the rice actin promoter (act1) and the selectable bar gene (bialaphos resistance gene) driven by the maize ubiquitin promoter (ubi1). Adjustments to various parameters such as gas pressure, microcarrier size and developmental stage of target tissue were essential for successful transient and stable transformation. Bombarded einkorn tissues are recalcitrant to regenerating plants, but certain modifications of the culture medium have been shown to increase the production of transgenic events. In various experiments, independent transgenic plants were produced at frequencies ranging from 0.0 to 0.6%. Molecular analysis, marker gene expression and herbicide treatment demonstrated that gfp/bar genes were stably integrated into the einkorn genome and successfully inherited over several generations. The transgenes, as dominant loci, segregated in both Mendelian and non-Mendelian fashion due to multiple insertions. Fertile homozygous T1-T2 populations of transgenic einkorn that are resistant to herbicides were selected.ConclusionTo the best of our knowledge, this is the first report of the production of genetically modified einkorn plants. We believe that the results of our research could be a starting point for the application of the current biotechnological-based technologies, such as transgenesis and genome editing, to accelerate comparative functional genomics in einkorn and other cereals.
| S-EPMC6199808 | biostudies-literature
Project description:Wheat leaf rust (Puccinia triticina) is one of the most significant fungal diseases of wheat, causing substantial yield losses worldwide. Infestation is currently being reduced by fungicide treatments and mostly vertical resistance. However, these measures often break down when the fungal virulence pattern changes, resulting in a breakdown of vertical resistances. In contrast, the prehaustorial resistance (phr) that occurs in the einkorn-wheat leaf rust interaction is race-independent, characterized by an early defense response of plants during the prehaustorial phase of infestation. Einkorn (Triticum monococcum) is closely related to Triticum urartu as a progenitor of wheat and generally shows a high level of resistance against leaf rust of wheat. Hence, einkorn can serve as a valuable source to improve the level of resistance to the pathogen in future wheat lines. In particular, einkorn accession PI272560 is known to exhibit a hypersensitive prehaustorial effector triggered immune reaction, preventing the infection of P. triticina. Remarkably, this effector-triggered immune reaction turned out to be atypical as it is non-race-specific (horizontal). To genetically dissect the prehaustorial resistance (phr) in PI272560, a biparental F2 population of 182 plants was established after crossing PI272560 with the susceptible T. boeoticum accession 36554. Three genetic maps comprising 2,465 DArT-seq markers were constructed, and a major QTL was detected on chromosome 5A. To locate underlying candidate genes, marker sequences flanking the respective QTL were aligned to the T. urartu reference genome and transcriptome data available from the parental accessions were used. Within the QTL interval of approximately 16.13 million base pairs, the expression of genes under inoculated and non-inoculated conditions was analyzed via a massive analysis of cDNA (MACE). Remarkably, a single gene located 3.4 Mbp from the peak marker within the major QTL was upregulated (20- to 95-fold) after the inoculation in the resistant accession in comparison to the susceptible T. boeoticum accession. This gene belongs to a berberine bridge enzyme-like protein that is suspected to interact on the plant surface with glycoside hydrolases (GH) secreted by the fungus and to induce a hypersensitive defense reaction in the plant after fungal infections.
| S-EPMC10626456 | biostudies-literature
Project description:Key messageThe new stem rust resistance gene Sr60 was fine-mapped to the distal region of chromosome arm 5AmS, and the TTKSK-effective gene SrTm5 could be a new allele of Sr22. The emergence and spread of new virulent races of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici; Pgt), including the Ug99 race group, is a serious threat to global wheat production. In this study, we mapped and characterized two stem rust resistance genes from diploid wheat Triticum monococcum accession PI 306540. We mapped SrTm5, a previously postulated gene effective to Ug99, on chromosome arm 7AmL, completely linked to Sr22. SrTm5 displayed a different race specificity compared to Sr22 indicating that they are distinct. Sequencing of the Sr22 homolog in PI 306540 revealed a novel haplotype. Characterization of the segregating populations with Pgt race QFCSC revealed an additional resistance gene on chromosome arm 5AmS that was assigned the official name Sr60. This gene was also effective against races QTHJC and SCCSC but not against TTKSK (a Ug99 group race). Using two large mapping populations (4046 gametes), we mapped Sr60 within a 0.44 cM interval flanked by sequenced-based markers GH724575 and CJ942731. These two markers delimit a 54.6-kb region in Brachypodium distachyon chromosome 4 and a 430-kb region in the Chinese Spring reference genome. Both regions include a leucine-rich repeat protein kinase (LRRK123.1) that represents a potential candidate gene. Three CC-NBS-LRR genes were found in the colinear Brachypodium region but not in the wheat genome. We are currently developing a Bacterial Artificial Chromosome library of PI 306540 to determine which of these candidate genes are present in the T. monococcum genome and to complete the cloning of Sr60.
| S-EPMC5814525 | biostudies-literature
Project description:For many agronomically important plant genes, only their position on a genetic map is known. In the absence of an efficient transposon tagging system, such genes have to be isolated by map-based cloning. In bread wheat Triticum aestivum, the genome is hexaploid, has a size of 1.6 x 10(10) bp, and contains more than 80% of repetitive sequences. So far, this genome complexity has not allowed chromosome walking and positional cloning. Here, we demonstrate that chromosome walking using bacterial artificial chromosome (BAC) clones is possible in the diploid wheat Triticum monococcum (A(m) genome). BAC end sequences were mostly repetitive and could not be used for the first walking step. New probes corresponding to rare low-copy sequences were efficiently identified by low-pass DNA sequencing of the BACs. Two walking steps resulted in a physical contig of 450 kb on chromosome 1A(m)S. Genetic mapping of the probes derived from the BAC contig demonstrated perfect colinearity between the physical map of T. monococcum and the genetic map of bread wheat on chromosome 1AS. The contig genetically spans the Lr10 leaf rust disease resistance locus in bread wheat, with 0.13 centimorgans corresponding to 300 kb between the closest flanking markers. Comparison of the genetic to physical distances has shown large variations within 350 kb of the contig. The physical contig can now be used for the isolation of the orthologous regions in bread wheat. Thus, subgenome chromosome walking in wheat can produce large physical contigs and saturate genomic regions to support positional cloning.
| S-EPMC27242 | biostudies-literature
Project description:Crop protection is an integral part of establishing food security, by protecting the yield potential of crops. Cereal aphids cause yield losses by direct damage and transmission of viruses. Some wild relatives of wheat show resistance to aphids but the mechanisms remain unresolved. In order to elucidate the location of the partial resistance to the bird cherry-oat aphid, Rhopalosiphum padi, in diploid wheat lines of Triticum monococcum, we conducted aphid performance studies using developmental bioassays and electrical penetration graphs, as well as metabolic profiling of partially resistant and susceptible lines. This demonstrated that the partial resistance is related to a delayed effect on the reproduction and development of R. padi. The observed partial resistance is phloem based and is shown by an increase in number of probes before the first phloem ingestion, a higher number and duration of salivation events without subsequent phloem feeding and a shorter time spent phloem feeding on plants with reduced susceptibility. Clear metabolic phenotypes separate partially resistant and susceptible lines, with the former having lower levels of the majority of primary metabolites, including total carbohydrates. A number of compounds were identified as being at different levels in the susceptible and partially resistant lines, with asparagine, octopamine and glycine betaine elevated in less susceptible lines without aphid infestation. In addition, two of those, asparagine and octopamine, as well as threonine, glutamine, succinate, trehalose, glycerol, guanosine and choline increased in response to infestation, accumulating in plant tissue localised close to aphid feeding after 24 h. There was no clear evidence of systemic plant response to aphid infestation.
| S-EPMC4982108 | biostudies-literature
Project description:Triticum monococcum subsp. monococcum as a first cultivated diploid wheat species possesses desirable agronomic and quality characteristics. Drought and salinity are the most dramatic environmental stress factors that have serious impact on yield and quality of crops; however, plants can use alternative defense mechanisms against these stresses. The posttranscriptional alteration of gene expression by microRNAs (miRNAs) is one of the most conserved mechanisms. In plant species including wheat genomes, miRNAs have been implicated in the management of salt and drought stress; however, studies on einkorn wheat (Triticum monococcum subsp. monococcum) are not yet available. In this study, we aimed to identify conserved miRNAs in einkorn wheat using next generation sequencing technology and bioinformatics analysis. In order to include a larger set of miRNAs, small RNA molecules from pooled plant samples grown under normal, drought, and salinity conditions were used for the library preparation and sequence analysis. After bioinformatics analysis, we identified 167 putative mature miRNA sequences belonging to 140 distinct miRNA families. We also presented a comparative analysis to propose that miRNAs and their target genes were involved in salt and drought stress control in addition to a comprehensive analysis of the scanned target genes in the T. aestivum genome.
| S-EPMC6451844 | biostudies-literature
Project description:Wheat being the important staple food crop plays a significant role in nutritional security. A wide variety of microbial communities beneficial to plants and contributing to plant health and production are found in the rhizosphere. The wheat microbiome encompasses an extensive variety of microbial species playing a key role in sustaining the physiology of the crop, nutrient uptake, and biotic/abiotic stress resilience. This report presents wheat microbiome analysis under six different farm practices, namely, organic (Org), timely sown (TS), wheat after pulse crop (WAPC), temperature-controlled phenotyping facility (TCPF), maize-wheat cropping system (MW), and residue burnt field (Bur), using 16S rRNA sequencing methodology. The soil samples collected from either side of the wheat row were mixed to get a final sample set for DNA extraction under each condition. After the data preprocessing, microbial community analysis was performed, followed by functional analysis and annotation. An abundance of the phylum Proteobacteria was observed, followed by Acidobacteria, Actinobacteria, and Gemmatimonadetes in the majority of the samples, while relative abundance was found to vary at the genus level. Analysis against the Carbohydrate-Active Enzymes (CAZy) database showed a high number of glycoside hydrolase genes in the TS, TCPF, and WAPC samples, while the Org, MW, and Bur samples predominantly had glycosyltransferase genes and carbohydrate esterase genes were in the lowest numbers. Also, the Org and TCPF samples showed lower diversity, while rare and abundant species ranged from 12 to 25% and 20 to 32% of the total bacterial species in all the sets, respectively. These variations indicate that the different cropping sequence had a significant impact on soil microbial diversity and community composition, which characterizes its economic and environmental value as a sustainable agricultural approach to maintaining food security and ecosystem health. IMPORTANCE This investigation examined the wheat microbiome under six different agricultural field conditions to understand the role of cropping pattern on soil microbial diversity. This study also elaborated the community composition, which has importance in economic (role of beneficial community leading to higher production) and environmental (role of microbial diversity/community in safeguarding the soil health, etc.) arenas. This could lead to a sustainable farming approach for food security and improved ecosystem health. Also, the majority of the microbes are unculturable; hence, technology-based microcultivation will be a potential approach for harnessing other cultured microorganisms, leading to unique species for commercial production. The outcome of this research-accelerated work can provide an idea to the scientists/breeders/agronomists/pathologists under the mentioned field conditions regarding their influence over their crops.
| S-EPMC9769940 | biostudies-literature
Project description:Wheat is among the important crops harnessed by humans whose breeding efforts resulted in a diversity of genotypes with contrasting traits. The goal of this study was to determine whether different old and new cultivars of durum wheat (Triticum turgidum L. var. durum) recruit specific arbuscular mycorrhizal (AM) fungal communities from indigenous AM fungal populations of soil under field conditions. A historical set of five landraces and 26 durum wheat cultivars were field cultivated in a humid climate in Eastern Canada, under phosphorus-limiting conditions. To characterize the community of AMF inhabiting bulk soil, rhizosphere, and roots, MiSeq amplicon sequencing targeting the 18S rRNA gene (SSU) was performed on total DNAs using a nested PCR approach. Mycorrhizal colonization was estimated using root staining and microscope observations. A total of 317 amplicon sequence variants (ASVs) were identified as belonging to Glomeromycota. The core AM fungal community (i.e., ASVs present in > 50% of the samples) in the soil, rhizosphere, and root included 29, 30, and 29 ASVs, respectively. ASVs from the genera Funneliformis, Claroideoglomus, and Rhizophagus represented 37%, 18.6%, and 14.7% of the sequences recovered in the rarefied dataset, respectively. The two most abundant ASVs had sequence homology with the 18S sequences from well-identified herbarium cultures of Funneliformis mosseae BEG12 and Rhizophagus irregularis DAOM 197198, while the third most abundant ASV was assigned to the genus Paraglomus. Cultivars showed no significant difference of the percentage of root colonization ranging from 57.8% in Arnautka to 84.0% in AC Navigator. Cultivars were generally associated with similar soil, rhizosphere, and root communities, but the abundance of F. mosseae, R. irregularis, and Claroideoglomus sp. sequences varied in Eurostar, Golden Ball, and Wakooma. Although these results were obtained in one field trial using a non-restricted pool of durum wheat and at the time of sampling, that may have filtered the community in biotopes. The low genetic variation between durum wheat cultivars for the diversity of AM symbiosis at the species level suggests breeding resources need not be committed to leveraging plant selective influence through the use of traditional methods for genotype development.
| S-EPMC7431883 | biostudies-literature
Project description:Puccinia triticina f. sp. tritici (Eriks.), the causal agent of leaf rust, causes substantial yield losses in wheat production. In wheat many major leaf rust resistance genes have been overcome by virulent races. In contrast, the prehaustorial resistance (phr) against wheat leaf rust detected in the diploid wheat Einkorn (Triticum monoccocum var. monococcum) accession PI272560 confers race-independent resistance against isolates virulent on accessions harboring resistance genes located on the A-genome of Triticum aestivum. Phr in PI272560 leads to abortion of fungal development during the formation of haustorial mother cells and to increased hydrogen peroxide concentration in comparison to the susceptible accession 36554 (Triticum boeoticum ssp. thaoudar var. reuteri). Increased peroxidase and endochitinase activity was detected in PI272560 within 6 h after inoculation (hai). Comparative transcriptome profiling using Massive Analysis of cDNA Ends (MACE) in infected and non-infected leaves detected 14220 differentially expressed tags in PI272560 and 15472 in accession 36554. Of these 2908 and 3004, respectively, could be assigned to Gene Ontology (GO) categories of which 463 were detected in both accessions and 311 were differentially expressed between the accessions. In accordance with the concept of non-host resistance in PI272560, genes with similarity to peroxidases, chitinases, β-1,3-glucanases and other pathogenesis-related genes were up-regulated within the first 8 hai, whereas up-regulation of such genes was delayed in 36554. Moreover, a Phosphoribulokinase gene contributing to non-host resistance in rice against stripe rust was exclusively expressed in the resistant accession PI272560. Gene expression underpinned physiological and phenotypic observations at the site of infection and are in accordance with the concept of non-host resistance.
| S-EPMC5101855 | biostudies-literature
Project description:BackgroundTriticum monococcum (2n) is a close ancestor of T. urartu, the A-genome progenitor of cultivated hexaploid wheat, and is therefore a useful model for the study of components regulating photomorphogenesis in diploid wheat. In order to develop genetic and genomic resources for such a study, we constructed genome-wide transcriptomes of two Triticum monococcum subspecies, the wild winter wheat T. monococcum ssp. aegilopoides (accession G3116) and the domesticated spring wheat T. monococcum ssp. monococcum (accession DV92) by generating de novo assemblies of RNA-Seq data derived from both etiolated and green seedlings.Principal findingsThe de novo transcriptome assemblies of DV92 and G3116 represent 120,911 and 117,969 transcripts, respectively. We successfully mapped ∼90% of these transcripts from each accession to barley and ∼95% of the transcripts to T. urartu genomes. However, only ∼77% transcripts mapped to the annotated barley genes and ∼85% transcripts mapped to the annotated T. urartu genes. Differential gene expression analyses revealed 22% more light up-regulated and 35% more light down-regulated transcripts in the G3116 transcriptome compared to DV92. The DV92 and G3116 mRNA sequence reads aligned against the reference barley genome led to the identification of ∼500,000 single nucleotide polymorphism (SNP) and ∼22,000 simple sequence repeat (SSR) sites.ConclusionsDe novo transcriptome assemblies of two accessions of the diploid wheat T. monococcum provide new empirical transcriptome references for improving Triticeae genome annotations, and insights into transcriptional programming during photomorphogenesis. The SNP and SSR sites identified in our analysis provide additional resources for the development of molecular markers.
| S-EPMC4018402 | biostudies-literature